Comparison of root canal shaping ability of different heat-treated NiTi single files: a micro-CT study

Objective: The purpose of this study was to evaluate the root canal shaping abilities of different heat-treated NiTi engine-­driven single files.
Method and materials: A total of 45 mandibular first molar teeth with a root canal curvature of between 25 and 35 degrees were selected for this in vitro study. The mesial roots were separated and scanned with micro-CT. The specimens were randomly divided into three groups. Root canal preparations were performed using HyFlex EDM OneFile in Group 1; OneCurve (25/06) in Group 2, and WaveOne Gold Primary in Group 3. Root canals were scanned again with micro-­ CT after root canal preparation. Apical transportation value and centering ability ratio of files were evaluated using the preinstrumentation and postinstrumentation micro-CT images at 1, 2, 3, 4, and 7 mm. The data were statistically analyzed using the Kruskal-Wallis test. The Bonferroni-Dunn test was used for multiple comparisons. The level of statistical significance was set at P < .05.
Results: There was no significant difference between the apical transportation values of experimental groups in mesiodistal direction (P > .05) and buccolingual direction (P > .05). The OneCurve file group showed better centering ability in the buccolingual direction than the WaveOne Gold file group at 4 mm (P = .048). The difference between the centering ability values of experimental groups was not significant at other levels (P > .05).
Conclusion: According to the results of this study, all tested single files caused apical transportation and showed similar centering ratio at most of the root sections.